1. Field of the Invention
The present invention relates to a misfuelling prevention device for a filler neck of a fuel tank, and also concerns a filler neck with a misfuelling prevention device.
2. Description of the Background Art
Motor vehicles such as passenger cars or transportation vehicles may be operated with gasoline or diesel, depending on the type of internal combustion engine used. In the event of misfuelling, for example when a diesel vehicle is filled with gasoline, the vehicle can sustain substantial damage when it is operated. Moreover, substantial costs can arise for emptying the fuel system after misfuelling has occurred.
In order to prevent misfuelling, the filler necks of fuel tanks are fitted with misfuelling prevention devices. Discharge pipes of delivery nozzles at gas stations have predetermined inside and outside diameters that depend on the fuel. Misfuelling prevention devices can prevent insertion of an unsuitable discharge pipe of a delivery nozzle on the basis of these geometric characteristics.
In this context, a safety element for a diesel fuel tank to prevent misfuelling is known from WO 2010/094508 A1, which corresponds to US 20110315682 (A1). The safety element comprises an insert element that can be installed in a filler neck of a vehicle fuel tank. The insert element has an elongated, tubular holding element, which can fit into the filler neck, with an inflow side and an outflow side. Held in the holding element is a shaped part that is elongated with respect to the holding element and whose free end face, which projects towards the inflow side, has a smaller outside diameter than the inside diameter of a discharge pipe of a diesel delivery nozzle while also having a larger outside diameter than the inside diameter of a discharge pipe of a gasoline delivery nozzle. In addition, an actuating element is provided that can be displaced coaxially to the filler opening on the inside wall of the holding element; this element is arranged so as to remain behind the face of the shaped part in the direction of the tank interior. During its displacement toward the interior of the tank, the actuating element is able to actuate a shutter arranged on the outflow side of the holding element.
In a misfuelling prevention element of this nature, problems can arise when fueling the vehicle from ordinary commercial fuel cans. In like manner, fuelling with delivery nozzles that provide the correct fuel but have the wrong discharge pipe diameter (too big or too small) at the delivery nozzle due to misassembly at the gas station may be hampered or prevented. A funnel can disable the misfuelling prevention in this case. However, a disadvantage here is that the funnel is wetted with diesel after use, and when subsequently stored in the vehicle can emit odor and diesel, thereby contaminating the passenger compartment or trunk.
In this context, a filler neck for a motor vehicle fuel tank is known from DE 10 2008 040 715 A1. The filler neck comprises a fueling opening for inserting a gas pump nozzle, a filling tube leading to the fuel tank, a misfuelling protection element located between the fueling opening and the filling tube, and an emergency fueling channel connecting the fueling opening and filling tube. The flow capacity of the emergency fueling channel is lower than the fueling speed of the fueling system of a gas station. The misfuelling protection can have a closure element that unblocks the filler neck only when the discharge pipe of a permissible gas pump nozzle is inserted, and otherwise blocks the filler neck. Examples of known closure elements include folding, pivoting, sliding, single-piece, and multiple-piece flap arrangements.